Phosphino−Arene Ruthenium Complexes Containing the Phosphorus Acid Anion {P(O)(OR)₂} as P-Donor

The cationic complex [Ru(OTf)(P(OH)Ph 2 ){Ph 2 P-(η 6 -arene)}]OTf, 2 ( 2a = 6‘-diphenylphosphino-1‘-naphthyl-η 6 (1 - 6) -naphthalene, 2b = 6,6‘-dimethoxy-2‘-diphenylphosphino-η 6 (1 - 6) -biphenyl), is shown to react with water/ tert -butyl alcohol/THF mixtures to afford [Ru(P( O)(OH) 2 {Ph 2 P-(η 6 -arene)}] 2 (OTf) 2, 4 . The solid-state structure of a derivative, [Ru{P( O)(OH)(OMe)}{Ph 2 P-(naphthyl-η 6 -naphthalene}] 2 (OTf) 2, 6, is reported and found to possess extremely asymmetric η 6 -arene bonding. Complexes 4 and 6, plus a mononuclear dimethoxy analogue, Ru(P( O)(OMe) 2 (Ph 2 P-(naphthyl-η 6 -naphthalene)](OTf), 8, represent the first examples of Ru-compounds that contain the phosphorus acid anion P( O)(OR) 2 (R = H and/or Me) as an anionic P-donor ligand. PGSE diffusion measurements are shown to be helpful in distinguishing between dinuclear oxygen bridging species and their mononuclear analogues.